Various ways of evaluating whether a container is leaky or not are known.
One known technique to evaluate leakiness of a container is the so called tracer gas technique. Thereby, a tracer gas as e.g. helium or another noble gas, nitrogen or hydrogen is introduced into the container. Then the container is closed. Transition of tracer gas through the now close encapsulation by the container is monitored—sniffed in the surrounding of the container for leak testing purposes. This technique is therefore also known as sniffer technique. For the purpose of sniffing whether tracer gas transits from the interior of the container to its surrounding it is known to apply mass spectrometry. With respect to such an approach attention is drawn e.g. on the DE 33 40 353.
The tracer gas which is present in the closed container in tracer gas technique is provided exclusively for leak testing purposes and is thus not or does not form part of the consumer product to be stored within the container.
This is even true if such tracer gas, e.g. Nitrogen, is filled into the container simultaneously with a consumer product but exclusively with the target of subsequent Nitrogen sniffing.
A further technique known for testing leakiness of close containers filled with a consumer product may be addressed, generically, as pressure course technique. Thereby, a pressure difference is applied between the inside and the surrounding of the close and filled container. This may be performed by lowering the pressure in the surrounding of the container relative to the pressure inside the closed container. This approach resides upon the fact that if the container is leaky, there occurs pressure equalization between the inside of the container and its surrounding. A course of pressure in the surrounding of the container may be sensed and exploited as a leak indicative signal. With respect to such leak testing techniques, realized by lowering the pressure in the surrounding of the container with respect to the (initial) pressure inside the container, we may refer e.g. to U.S. Pat. Nos. 5,029,464, 5,170,660, 5,239,859, 5,915,270, all of the same applicant as the present application.
An improvement over the technique just addressed, especially for leak testing closed containers with a consumer product comprising a free liquid which covers at least a part of the inner surface of the container may be addressed generically as vaporizing technique. In this technique the pressure in the surrounding of the container is lowered at least to vapor pressure of a liquid component of the consumer product. There results that any such liquid component which is exposed, as through a leak, to the addressed vapor pressure is high-rate evaporated into the surrounding. This leads to a highly significant, accurately detectable leak indicative pressure course in the surrounding. With respect to this technique we may refer to U.S. Pat. Nos. 5,907,093, 6,082,184, 6,202,477, 6,305,215, 6,439,033, 6,575,016, 6,829,936, 7,000,456 and further related patent documents, all of the same applicant as the present application.
Moreover, a further known leak testing technique is based on mechanical squeezing the close containers filled with a consumer product as e.g. disclosed in U.S. Pat. No. 6,439,039 of the same applicant and/or are based on impedance measurement in the surrounding of the closed container filled with a consumer product as disclosed in the U.S. Pat. No. 5,962,776, also of the same applicant as the present application.